Margaret Thatcher deliberately lied to miners about the extent of plans to close pits during the bitter year-long dispute that began 30 years ago this month, according to evidence uncovered by a former BBC Industrial and Political Correspondent.

A detailed analysis by Nicholas Jones of UK Government papers from 1984 released last month shows that the then Prime Minister was personally involved in a calculated campaign of misinformation aimed at persuading miners and the public that union leader Arthur Scargill had no grounds for saying that the National Coal Board (NCB) had a closure hit-list of 70 pits.

In fact, released Cabinet papers show that NCB chairman Ian MacGregor told the Government he intended to close as many as 75 pits with the loss of 64,000 jobs.

The South Wales coalfield was the biggest victim – a Cabinet Office note from the time said: “The manpower reductions would bite heavily in particular areas: two-thirds of Welsh miners would become redundant, 35% of miners in Scotland, 48% in the north east, 50% in South Yorkshire and 46% in the South Midlands”.

In a chapter of a book edited by Granville Williams called Settling Scores, published today by the Campaign for Press & Broadcasting Freedom, Jones writes: “{Margaret Thatcher} personally approved a letter which flatly rejected Scargill’s claim that MacGregor intended to ‘butcher’ the coal industry; it stated that the NCB was seeking ‘20,000 voluntary redundancies’. not the 70,000 claimed by the National Union of Mineworkers (NUM).

“The letter was delayed for a week after she asked for a further redrafting and it was finally sent {to miners} on June 21 1984, three and a half months into the strike.”

Commenting on Scargill’s claims, the letter – sent in the name of MacGregor, but personally approved by Mrs Thatcher – said: “If these things were true I would not blame miners for getting angry or for being deeply worried. But these things are absolutely untrue. I state categorically and solemnly you have been deliberately misled.”

Jones, from Abergavenny, also outlines how orders were given that further documents related to the true closure plan were not to be copied. Cabinet papers show Mrs Thatcher agreed that no record of Energy Secretary Peter Walker’s report on MacGregor’s plan should be circulated.

Meanwhile calls for a public inquiry into the year-long miners’ strike are being stepped up as communities across the country gear up to commemorate the 30th anniversary of the start of the most bitter industrial conflict in living memory.

A series of events will be held by miners, their families, supporters and union activists in the coming weeks, while the anger and bitterness which characterised the dispute will be re-kindled.

The recent revelation in government papers released by the National Archives that Margaret Thatcher secretly considered calling out the troops at the height of the strike has heightened the belief that a full-blown inquiry should be held.

Labour MP Ian Lavery, a former president of the NUM, has tabled an early day motion in Parliament, which “regrets that nearly 30 years after the strike ended, there are still men who were wrongly arrested or convicted during the dispute, who have never received justice”. More than 60 MPs are supporting the motion.

Mr Lavery said he would continue pressing for an inquiry into the events of 30 years ago.

He said: “People who live in great mining communities across the UK have not forgotten the strike and they will never forget.

“Passions have not waned. In 100 years time I am confident that people will say that their great grandfather was a miner and was proud to have taken part in the strike. That is how deep this thing runs.”

Mr Lavery said the archive papers revealing that ministers considered declaring a state of emergency, amid fears that union action could destroy the government, backed up his belief that MPs and the public were misled.

“The Prime Minister deliberately misled Parliament and the public by saying the NUM was scaremongering about pit closures.

“They played down the impact of the strike, but it is now clear they were considering bringing in the troops.”

The strike started in early March 1984 over pit closures planned by the state-owned National Coal Board and pitted Mrs Thatcher’s government against the NUM and its fiery president Arthur Scargill. Mr Scargill always maintained that the government planned mass pit closures as well as attacking the union, a sentiment which was backed up by a now-released note from an official at 10 Downing Street that said the strike was a “unique opportunity to break the power of the militants in the NUM”.

Mr Lavery said the NUM also had a social structure in communities, with officials helping to deal with any problems, and that had been “totally destroyed.”

“Many coal communities are still suffering from the closure of pits because nothing has replaced coal, but it is also devastating to see the impact of the demise of the NUM in these areas too,” he said.

The strike started in Yorkshire but rapidly escalated, with thousands of police officers drafted into Nottinghamshire, the county which became a battleground as some miners continued to work.

Toni Bennett helped set up a women’s group in Bolsover, which distributed food and other supplies to picket lines across Derbyshire and Nottinghamshire.

“Nottinghamshire miners had a hard time because the area became known for the scabs. My husband went on strike, and I still feel very bitter towards the scabs,” she said. “There are still families today who don’t talk to each other as a result of the strike. I moved here from London 40 years ago and was struck by the community spirit, with people looking out for each other. That has gone. Young people can’t get any work.”

Pressure is also mounting for a full public inquiry into one of the most violent days of the miners strike when 96 people were arrested and 51 injured during clashes between pickets and police.

The day started peacefully on June 18 in 1984, when pickets started arriving at the Orgreave coking plant in Yorkshire but within hours there were pitched battles between miners and police, many on horseback.

The police maintain they were subjected to a hail of missiles from among the thousands of pickets who had gathered outside the plant to try to prevent lorries leaving, but the pickets say the police over-reacted.

Joe Rollin, chairman of the Orgreave Truth and Justice Campaign, said he believed the police were sending out a political message to miners that they would not tolerate mass picketing: “We think that was a political decision. The ramifications are still being felt, with lasting damage to coalfield communities which suffer high levels of unemployment and drug and alcohol-related problems.”